[Technical Field]
The present disclosure relates to a steering control apparatus.
[Related Art]
Steering control apparatuses calculate an assistance amount by controlling a steering torque to match a target steering torque calculated based on load. Among the steering control apparatuses, a steering control apparatus that compensates the assistance amount is known.
For example, Japanese Patent Publication No. 5533822 discloses an electric power steering control apparatus in which basic compensation amounts calculated by a plurality of basic compensation amount calculating means are weighted and added. An assistance compensation amount is thereby generated. A basic assistance amount is then corrected based on the generated assistance compensation amount.
JP-A-2015-168346 discloses an electric power steering apparatus in which a reverse input that acts on a steering wheel from a wheel side is detected or estimated. A frequency component of a specific band of the reverse input is extracted. Then, a phase of the extracted specific frequency component is adjusted, and a compensation component for an assistance component is calculated based on the reverse input. As a result, the reverse input is transmitted to a steering mechanism such that, of the reverse input, road-surface information, such as a road-surface reaction force, is amplified as necessary information and disturbances, such as braking vibrations, are suppressed as unnecessary information.
In the apparatus in Japanese Patent Publication No. 5533822, the weight at each frequency band is adjusted for a plurality of frequency characteristics. As a result, characterization of a vehicle can be arbitrarily performed. However, to achieve desired characteristics, the use of a high-order filter, as well as a high level of skills in design and adaptation, is required.
In addition, the frequency at which transmission characteristics are to be changed and a center frequency of a bandpass filter at which weighting and addition are to be performed do not necessarily match. Furthermore, the degree of change in the transmission characteristics differs based on the amount of the main assistance component, that is, the weight.
In the apparatus in JP-A-2015-168346, the compensation amount calculated to amplify only the necessary reverse input component is added to the assistance component, and the result is transmitted to the steering mechanism. However, as disclosed in FIG. 4 of JP-A-2014-31103, for example, the transmission characteristics from a wheel to a steering wheel significantly changes based, not only on the specifications of the mechanism, but also assistance control. Therefore, phase design and adaptation matching the senses of a driver not easy to perform.